US10727362B2 - Methods of hermetically sealing photovoltaic modules - Google Patents

Abstract

In various embodiments, photovoltaic modules are hermetically sealed by providing a first glass sheet, a photovoltaic device disposed on the first glass sheet, and a second glass sheet, a gap being defined between the first and second glass sheets, disposing a glass powder within the gap, and heating the powder to seal the glass sheets.

Description

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 15/896,180, filed Feb. 14, 2018, which is a continuation of U.S. patent application Ser. No. 14/986,983, filed Jan. 4, 2016, which is a continuation of U.S. patent application Ser. No. 14/457,922, filed Aug. 12, 2014, which claims the benefit of and priority to U.S. Provisional Patent Application No. 61/868,203, filed Aug. 21, 2013, the entire disclosure of each of which is hereby incorporated herein by reference.

TECHNICAL FIELD

In various embodiments, the present invention relates to photovoltaic devices, and in particular to glass-sealed photovoltaic modules.

BACKGROUND

Current state-of-the-art photovoltaic (PV) modules based on silicon (Si) wafer technology employ a front glass/encapsulant/wafer/encapsulant/backsheet structure. Polyvinyl fluoride (e.g., Tedlar® from DuPont) is the most commonly used backsheet in wafer-based Si PV modules. This material is inherently transparent for water vapor and gases—i.e., it does not enable or maintain a hermetic seal. Thin-film PV modules based on amorphous Si (a-Si), CdTe, or copper indium gallium selenide (CuIn_xGa_1-xSe₂or CIGS) most often utilize a glass-glass architecture with one of the glass sheets either serving as the substrate (CIGS) or superstrate (a-Si, CdTe) onto which the active PV material is deposited directly. The function of the second glass sheet is to serve as either the protective top (CIGS) or back cover (a-Si, CdTe). Both sheets of glass are held together with a single encapsulant layer. For practical purposes the 1.8-4 mm-thick sheets of glass are impermeable to water and gases. However, moisture and gas ingress can occur along the edges of the glass/encapsulant/glass sandwich. Exposure to such moisture can result in issues such as corrosion, decreased minority carrier lifetime, and increased series resistance, deleteriously impacting the performance and lifetime of the PV module. To slow down moisture ingress and gas permeation, butyl-based edge seals are typically applied, as butyl rubber has water vapor transmission rates (WVTR) on the order of 10⁻⁶g/m²-day, orders of magnitude below the WVTR for typical encapsulant materials.

While the WVTR value for butyl is considered to be adequate for long-term protection, the overall vulnerability of a device to moisture usually derives less from the bulk diffusivity of the butyl than from the durability of the interface between the butyl and the glass. Adhesion promoters to establish coupling of the polymer to the glass are typically added to the butyl, but the resulting bonds tend to be weak and easily damaged by ultraviolet radiation, prolonged exposure to elevated temperatures, and humidity—i.e., conditions in which PV modules are commonly deployed. Stresses present between the two sheets of glass can further strain the glass/butyl interfaces. Hence, even for such edge-sealed glass-glass structures, moisture penetration is a common field failure mode. Thus, there is a need for hermetically sealed modules and techniques that enable environmental protection of thin-film PV devices and which are superior to current butyl-rubber-based solutions.

SUMMARY

Embodiments of the present invention provide PV modules hermetically sealed against environmental contamination via edge seals consisting entirely of glass. While preferred embodiments of the invention utilize “thin-film” PV modules featuring PV devices based on CIGS, a-Si, or CdTe, other embodiments of the invention utilize PV devices based on crystalline Si (e.g., in wafer or ribbon form) or III-V semiconductors such as GaAs or InP (e.g., in wafer form) or solid-state dye-sensitized perovskite material (organic-inorganic hybrid). As utilized herein, “PV devices” are the active PV materials within PV modules, and these typically include or consist essentially of materials forming one or more p-n or p-i-n junctions that each absorb at least a portion of the solar spectrum and convert it into electricity. In preferred embodiments, a powder consisting essentially of or consisting of glass is utilized to seal a PV device fronted and backed by glass sheets, thereby forming a sealed PV module. The glass powder is locally heated to a temperature higher than the melting point, glass transition temperature, and/or softening point of the powder such that the powder softens and/or flows into a unified mass that bonds with the glass sheets to form a hermetic seal.

Advantageously, embodiments of the present invention increase the active area of the PV module, and hence the power output for a fixed PV module size. Typical safety requirements, e.g., IEC or UL, mandate a minimum insulation distance from the current-carrying live parts inside a PV module to the outside edge of the module—i.e., the clearance and creepage distance. Such “edge delete” losses depend on various aspects such as the total system voltage or micro-environment (e.g., pollution degree and altitude), but are typically at the order of 8-15 mm. As conventional polymeric edge seals can fail over time, the insulation against electrical shock is compromised and, in the case of moisture ingress, current can track over the glass or polymer surface from the module circuit to its edge. In contrast, the glass-based seals in accordance with embodiments of the present invention are truly durable cemented joints retaining their superior electrical insulation properties over time. These seals allow the clearance—i.e., the edge delete—to be smaller, in turn proportionally increasing the power output from the PV module for the same total area.

In addition, the polymeric encapsulant (filler sheet)—e.g., EVA, PVB, polyolefin, ionomers, TPU—conventionally utilized to bond glass sheets together may be eliminated in accordance with embodiments of the present invention. After the cost of the glass sheets, such filler sheets are typically the most expensive elements of thin-film PV modules. Thus, embodiments of the invention enable significant reductions in material cost. Furthermore, elimination of polymeric filler sheets and the conventional butyl rubber edge seals also enables PV modules in accordance with embodiments of the invention to obtain higher fire ratings. Moreover, elimination of such conventional polymer-based filler sheets and edge seals obviates the need for the slow and capital-intensive lamination step, resulting in additional manufacturing cost savings for PV modules in accordance with embodiments of the present invention.

PV modules that are hermetically sealed in accordance with embodiments of the present invention exhibit advantageously enhanced durability in climates and/or ambient conditions that have high relative humidity, e.g., coastal or equatorial locations. In addition, since PV modules and devices sealed in accordance with embodiments of the invention do not rely on seals based on glass-polymer adhesion, they are less susceptible than to fatigue under conditions such as UV radiation, elevated temperature, and high humidity or moisture levels. Glass-polymer bonds also tend to be susceptible to failure due to mechanical stresses from, e.g., etch pinch during module lamination.

In an aspect, embodiments of the invention feature a photovoltaic module that includes, consists essentially of, or consists of a first glass sheet, a photovoltaic device disposed on the first glass sheet, a second glass sheet disposed over and in contact with at least a portion of the photovoltaic device, and a layer of melted glass powder. The first glass sheet and the second glass sheet have a gap therebetween spanned, over only a portion of an area of the gap, by the photovoltaic device, and the layer of melted glass powder seals the gap between the first and second glass sheets at an edge region proximate an edge of at least one of the first or second glass sheets so as to hermetically seal the photovoltaic device.

Embodiments of the invention may include one or more of the following in any of a variety of different combinations. The photovoltaic device may include, consist essentially of, or consist of an active region including, consisting essentially of, or consisting of one or more p-n or p-i-n junctions. The photovoltaic module may include (i) a first substrate layer disposed between the active region and the first glass sheet and/or (ii) a second substrate layer disposed between the active region and the second glass sheet. The first and/or second substrate layers may each include, consist essentially of, or consist of a metal foil and/or a polymer layer. A conductive bus ribbon may be electrically coupled to the photovoltaic device and may extend out from the first and second glass sheets in contact with the layer of melted glass powder. In a region where the conductive bus ribbon extends out from the first and second glass sheets, the conductive bus ribbon may be (i) disposed in contact with both the first and second glass sheets, (ii) disposed in contact with the first glass sheet and the layer of melted glass powder, but not with the second glass sheet, (iii) disposed in contact with the second glass sheet and the layer of melted glass powder, but not with the first glass sheet, or (iv) disposed in contact with the layer of melted glass powder, but not with the first or second glass sheets. The melted glass powder may include a colorant or other absorber utilized to, e.g., locally increase the absorption of particular wavelengths of light.

The photovoltaic device may include, consist essentially of, or consist of multiple junctions, each of which is a p-n junction or a p-i-n junction. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of amorphous silicon. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of CdTe. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of chalcopyrite (Cu(In,Ga)(S,Se)₂). The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of kesterite (Cu₂(Zn,Fe)Sn(S,Se)₄). The photovoltaic device may include, consist essentially of, or consist of crystalline silicon and/or GaAs. The photovoltaic device may include, consist essentially of, or consist of solid-state dye-sensitized perovskite material (organic-inorganic hybrid). The composition of the melted glass powder may be substantially the same as the composition of the first and/or second glass sheets. The composition of the melted glass powder may be different from a composition of either of the first or second glass sheets (i.e., different from the compositions of both of the first and second glass sheets).

In another aspect, embodiments of the invention feature a method of hermetically sealing a photovoltaic module. First, a structure is provided. The structure includes, consists essentially of, or consists of a first glass sheet, a photovoltaic device disposed on the first glass sheet, and a second glass sheet disposed over and in contact with at least a portion of the photovoltaic device, the first glass sheet and the second glass sheet defining a gap therebetween spanned, over only a portion of an area of the gap, by the photovoltaic device. A powder is disposed within the gap at an edge region proximate an edge of at least one of the first or second glass sheets. The powder includes, consists essentially of, or consists of glass. The powder is heated within the gap to seal the first and second glass sheets at the edge region with a layer of melted glass powder.

Embodiments of the invention may include one or more of the following in any of a variety of different combinations. Heating the powder may include, consist essentially of, or consist of application of laser energy to the powder (e.g., through one or both of the first or second glass sheets). The photovoltaic device may include, consist essentially of, or consist of an active region including, consisting essentially of, or consisting of one or more p-n or p-i-n junctions. The photovoltaic module may include (i) a first substrate layer disposed between the active region and the first glass sheet and/or (ii) a second substrate layer disposed between the active region and the second glass sheet. The first and/or second substrate layers may each include, consist essentially of, or consist of a metal foil and/or a polymer layer. A conductive bus ribbon may be electrically coupled to the photovoltaic device and may extend out from the first and second glass sheets in contact with the layer of melted glass powder (i.e., the powder may be melted at least partially around the bus ribbon in the edge region). In a region where the conductive bus ribbon extends out from the first and second glass sheets, the conductive bus ribbon may be (i) disposed in contact with both the first and second glass sheets, (ii) disposed in contact with the first glass sheet and the layer of melted glass powder, but not with the second glass sheet, (iii) disposed in contact with the second glass sheet and the layer of melted glass powder, but not with the first glass sheet, or (iv) disposed in contact with the layer of melted glass powder, but not with the first or second glass sheets. The powder may include a colorant or other absorber utilized to, e.g., locally increase the absorption of particular wavelengths of light.

The photovoltaic device may include, consist essentially of, or consist of multiple junctions, each of which is a p-n junction or a p-i-n junction. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of amorphous silicon. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of CdTe. The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of chalcopyrite (Cu(In,Ga)(S,Se)₂). The photovoltaic device may be a thin-film photovoltaic device that includes, consists essentially of, or consists of kesterite (Cu₂(Zn,Fe)Sn(S,Se)₄). The photovoltaic device may include, consist essentially of, or consist of crystalline silicon and/or GaAs. The photovoltaic device may include, consist essentially of, or consist of solid-state dye-sensitized perovskite material (organic-inorganic hybrid). The composition of the melted glass powder may be substantially the same as the composition of the first and/or second glass sheets. The composition of the melted glass powder may be different from a composition of either of the first or second glass sheets (i.e., different from the compositions of both of the first and second glass sheets).

These and other objects, along with advantages and features of the present invention herein disclosed, will become more apparent through reference to the following description, the accompanying drawings, and the claims. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations. As used herein, the terms “approximately” and “substantially” mean±10%, and in some embodiments, ±5%. The term “consists essentially of” means excluding other materials that contribute to function, unless otherwise defined herein. Nonetheless, such other materials may be present, collectively or individually, in trace amounts. For example, a structure consisting essentially of glass will generally include only glass and only unintentional impurities (which may be metallic or non-metallic) that may be detectable via chemical analysis but do not contribute to function. For example, a powder or seal consisting essentially of glass typically does not incorporate organic fillers, binders, solvents, glass frit, frit material(s), glass solder, and/or melting-point reduction agents such as Pb.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:

FIG. 1 is a schematic cross-section of a portion of a photovoltaic module being sealed via application of thermal energy in accordance with various embodiments of the invention;

FIG. 2 is a schematic plan view of a photovoltaic module in accordance with various embodiments of the invention; and

FIGS. 3A-3D are schematic cross-sections of edge portions of sealed photovoltaic modules in accordance with various embodiments of the invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a portion of aPV module100 being sealed at an edge region via application of thermal energy in accordance with embodiments of the present invention. As shown, thePV module100 includes anactive PV device110, one or moreconductive bus ribbons120, alower glass sheet130, and anupper glass sheet140. While preferred embodiments of the invention utilize thin-film PV modules100 featuringPV devices110 based on CIGS, a-Si, or CdTe, other embodiments of the invention utilizePV devices110 based on crystalline Si (e.g., in wafer or ribbon form) or III-V semiconductors such as GaAs or InP (e.g., in wafer form) or solid-state dye-sensitized perovskite material (organic-inorganic hybrid incorporating a dye such as hybrid perovskite CH₃NH₃PbI₃dye). The one ormore bus ribbons120 are electrically coupled to thePV device110 and extend beyond thelower glass sheet130 and upper glass sheet140 (seeFIG. 2), thereby enabling external electrical contact to thePV device110. The bus ribbon(s) may include, consist essentially of, or consist of one or more highly electrically conductive metals, e.g., aluminum, copper, or a multilayer stack of one or more aluminum layers and one or more copper layers. In various embodiments, conventional alkali alkaline-earth silicate glasses (i.e., soda lime glass) are utilized as one or both of thelower glass sheet130 and theupper glass sheet140, as such glasses are less expensive than, e.g., alkali-lead silicate glass, alkaline-earth aluminosilicate glass, and borosilicate glass, any of which might also be utilized. In an example, one or both of thelower glass sheet130 and theupper glass sheet140 have a composition that is approximately 71% SiO₂, approximately 15% alkali (e.g., primarily Na₂O, but may also include K₂O), approximately 13-16% alkaline earths (e.g., CaO+MgO), approximately 0-2% Al₂O₃, and, in some embodiments, BaO.

As shown inFIG. 1, agap150 between theglass sheets130,140 is partially or substantially filled with aglass powder160 at or near the edge of at least one of theglass sheets130,140, and theglass powder160 is then melted via application ofthermal energy170. Theglass powder160 may be dispensed within the gap150 (or on at least one of theglass sheets130,140 in the vicinity ofgap150 prior to one or both of theglass sheets130,140 being applied to the PV device110) as a bead. In various embodiments of the invention, thegap150 between theglass sheets130,140 has a thickness (i.e., height) between approximately 50 μm and approximately 500 μm, for example, between approximately 50 μm and 100 μm. Theglass powder160 may have a grain size (or range of grain sizes) optimized to allow fast melting/fusing and to provide a geometrically stable powder track (e.g., width and height) during powder dispense. For example, theglass powder160 may have a grain size between approximately 0.1 μm and approximately 10 μm, or even between approximately 0.1 μm and 1 μm. In preferred embodiments of the invention, theglass powder160 does not require any preconditioning after it has been dispensed onto one or both of theglass sheets130,140, i.e. theupper glass sheet140 may be placed on top immediately after theglass powder160 is dispensed, and the sealing step is conducted in one operation.

The meltedglass powder160 fuses into a solid glass seal filling thegap150 between thesheets130,140 and bonding to thesheets130,140, thereby forming a hermetic seal that is much more durable than similar seals utilizing polymer-based fills. In addition, theglass powder160 may consist entirely or essentially of glass, in contrast with glass-frit materials that incorporate organic fillers, binders, solvents, and/or melting-point reduction agents such as Pb. The glass powder may include colorants or other absorbers utilized to locally increase the absorption of particular wavelengths of light. However, in preferred embodiments, theglass powder160 utilized to seal thegap150 has the same composition as at least one of theglass sheets130,140. Theglass powder160 may include, consist essentially of, or consist of a low-melting glass that fuses withglass sheets130,140 upon melting. The melting point of theglass powder160 may be, for example, between approximately 200° C. and approximately 550° C., or even between approximately 200° C. and approximately 400° C. In some embodiments, theglass powder160 includes, consists essentially of, or consists of a zinc-silicoborate glass and/or a binary or ternary mixture of thallium, arsenic and sulfur.

In preferred embodiments of the invention,pressure180 is applied to one or both of theglass sheets130,140 in order to facilitate seal formation when theglass powder160 is heated. Moreover, various embodiments utilize laser energy as thethermal energy170 to heat and melt theglass powder160 during seal formation. The laser utilized to impart thethermal energy170 may emit substantially red light. Thelaser energy170 may be applied via one or multiple passes along the edges ofglass sheets130,140 by a laser, depending upon how well the beam energy is coupled into theglass powder160 and how best to minimize any thermally induced stress in theglass sheets130,140 along the seal. In some embodiments, thelaser energy170 is pulsed in order to prevent excess heating of thePV device110 and/or other parts ofmodule100 away from the edge region being sealed.

In other embodiments, other techniques for localized heating, e.g., inductive heating or application of a torch or other heat source, are used to partially or substantially completely melt theglass powder160. While theglass powder160 is at least partially melted to form the hermetic edge seal, thePV device110 within themodule100 is preferably not exposed to temperatures sufficiently elevated to damage or degrade the device (via, e.g., interdiffusion, melting, etc.). For example, in various embodiments of the present invention, the localized heating temperature does not exceed 400-500° C. for times of ≤1 minute, does not exceed 300-400° C. for times of ≤1-3 minutes, and/or does not exceed 200-300° C. for times of ≤3-10 minutes.

As mentioned above, in order to enable electrical contact between the encapsulatedPV device110 and outside electronics and/or systems, one or moreconductive bus ribbons120 may be electrically coupled to the sealedPV device110 and extend out of the sealedmodule100 through the layer of meltedglass powder160. An example is shown in the plan view ofFIG. 2, in whichupper glass sheet140 is omitted for clarity. ThePV device110 itself includes or consists essentially of one or more p-n and/or p-i-n junctions (i.e., homojunctions and/or heterojunctions), and may be fabricated from a-Si, CdTe, or a chalcopyrite (Cu(In,Ga)(S,Se)₂) such as CIGS or a kesterite (Cu₂(Zn,Fe)Sn(S,Se)₄) such as CZTS (copper zinc tin sulfide). Other embodiments of the invention utilizePV devices110 based on crystalline Si (e.g., in wafer or ribbon form) or III-V semiconductors such as GaAs or InP (e.g., in wafer form) or solid-state dye-sensitized perovskite material (organic-inorganic hybrid). The junction(s) ofPV device110 may be in direct contact with one or both of theglass sheets130,140 (if, e.g., theglass sheets130,140 are utilized as a substrate or superstrate for the PV device110), or thePV device110 may incorporate a substrate layer (e.g., a foil of a metal or another conductor, or of a polymer such as polyimide) below and/or above the PV device junctions and in contact with one or both of theglass sheets130,140. In embodiments in which a substrate layer is disposed above the PV device junctions, the “substrate” is understood to include “superstrate” configurations as they are known in the art.

As shown inFIGS. 3A-3D, theconductive bus ribbon120 and glass-powder seal160 may have any of several different configurations. For example, in the configuration depicted inFIG. 3A, theconductive bus ribbon120 is in contact with both theupper glass sheet140 and thelower glass sheet130, and theglass powder160 seals the remaining portion of thegap150 between theglass sheets130,140 and contacts thebus ribbon120. InFIGS. 3B and 3C, thebus ribbon120 is in contact with only the lower glass sheet130 (FIG. 3B) or upper glass sheet140 (FIG. 3C), and theglass powder160 seals the remaining portion of thegap150 between theglass sheets130,140 and above or below thebus ribbon120. InFIG. 3D, thebus ribbon120 extends through the glass-powder seal160 without contacting either of theglass sheets130,140. Depending upon the compositions of thebus ribbon120 and theglass sheets130,140, the configurations ofFIGS. 3B-3D may result in a metal-glass seal between thebus ribbon120 and theglass powder160 upon application of the localizedthermal energy170.

During the edge-seal formation, the surfaces of theglass sheets130,140 to be joined together may be treated (e.g., cleaned to remove bond-impeding contamination or have thin surface layers removed) prior to the application offorce180 andlocalized heating170. Theforce180 is typically applied to the surface of at least one of theglass sheets130,140 until theglass powder160 has melted, sealed the edge region, and then cooled to form a solid (or at least semi-solid) phase. After the localized heating and seal formation, any localized stress at the sealed edge region may be at least partially reduced via annealing of the sealed module100 (or at least the sealed edge region) at a moderate temperature (e.g., at a temperature lower than the melting point and/or the softening point of the glass powder160).

The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive.

Claims (18)

What is claimed is:

1. A method of hermetically sealing a photovoltaic module, the method comprising:

providing a structure comprising:

a first glass sheet,

disposed on the first glass sheet, a photovoltaic device configured to absorb at least a portion of a solar spectrum and convert the at least a portion of the solar spectrum into electricity,

a second glass sheet disposed over the photovoltaic device, the first glass sheet and the second glass sheet thereby defining a gap at least a portion of which is spanned by the photovoltaic device, and

a powder consisting essentially of glass disposed within the gap at an edge region proximate an edge of at least one of the first glass sheet or the second glass sheet, the powder being free of glass frit, frit material, organic fillers, binders, solvents, and lead; and

thereafter, heating the powder within the gap to seal the first and second glass sheets at the edge region with a layer of melted glass powder,

wherein a temperature of the photovoltaic device does not exceed 300° C. during heating of the powder.

2. The method ofclaim 1, wherein the temperature of the photovoltaic device does not exceed 200° C. during heating of the powder.

3. The method ofclaim 1, wherein (i) the structure comprises a conductive bus ribbon electrically coupled to the photovoltaic device and extending from the edge region, and (ii) when the edge region is sealed, the conductive bus ribbon extends from and is in direct mechanical contact with the layer of melted glass powder.

4. The method ofclaim 3, wherein, at the sealed edge region, the conductive bus ribbon is disposed in direct mechanical contact with both the first and second glass sheets.

5. The method ofclaim 3, wherein, at the sealed edge region, the conductive bus ribbon is disposed in direct mechanical contact with the first glass sheet and the layer of melted glass powder, but not with the second glass sheet.

6. The method ofclaim 3, wherein, at the sealed edge region, the conductive bus ribbon is disposed in direct mechanical contact with the second glass sheet and the layer of melted glass powder, but not with the first glass sheet.

7. The method ofclaim 3, wherein, at the sealed edge region, the conductive bus ribbon is disposed in direct mechanical contact with the layer of melted glass powder, but not with the first or second glass sheets.

8. The method ofclaim 1, wherein heating the powder comprises application of laser energy to the powder.

9. The method ofclaim 1, wherein the powder and the first and second glass sheets at the edge region are heated only after the powder is dispensed at the edge region.

10. The method ofclaim 1, wherein a grain size of the powder ranges between approximately 0.1 μm and approximately 10 μm.

11. The method ofclaim 1, wherein the powder is heated via induction heating.

12. The method ofclaim 1, wherein a composition of the powder is the same as a composition of the first glass sheet and/or a composition of the second glass sheet.

13. A method of hermetically sealing a photovoltaic device, the method comprising:

providing a structure comprising:

a first glass sheet,

disposed on the first glass sheet, a photovoltaic device configured to absorb at least a portion of a solar spectrum and convert the at least a portion of the solar spectrum into electricity,

a second glass sheet disposed over the photovoltaic device, the first glass sheet and the second glass sheet thereby defining a gap at least a portion of which is spanned by the photovoltaic device, and

a powder consisting essentially of glass disposed within the gap at an edge region proximate an edge of at least one of the first glass sheet or the second glass sheet, the powder being free of glass frit, frit material, organic fillers, binders, solvents, and lead; and

thereafter, heating the powder within the gap to seal the first and second glass sheets at the edge region with a layer of melted glass powder,

wherein heating the powder comprises application of red laser energy to the powder.

14. The method ofclaim 8, wherein the laser energy is applied (i) through the first glass sheet toward the powder and (ii) through the second glass sheet toward the powder.

15. The method ofclaim 8, wherein the laser energy is applied (i) through the first glass sheet toward the powder or (ii) through the second glass sheet toward the powder.

16. The method ofclaim 8, wherein the laser energy is pulsed during application thereof.

17. A method of hermetically sealing a photovoltaic module, the method comprising:

providing a structure comprising:

a first glass sheet,

disposed on the first glass sheet, a photovoltaic device configured to absorb at least a portion of a solar spectrum and convert the at least a portion of the solar spectrum into electricity,

a second glass sheet disposed over the photovoltaic device, the first glass sheet and the second glass sheet thereby defining a gap at least a portion of which is spanned by the photovoltaic device, and

a powder consisting essentially of glass disposed within the gap at an edge region proximate an edge of at least one of the first glass sheet or the second glass sheet, the powder being free of glass frit, frit material, organic fillers, binders, solvents, and lead;

thereafter, heating the powder within the gap to seal the first and second glass sheets at the edge region with a layer of melted glass powder; and

after the first and second glass sheets are sealed at the edge region, (i) cooling the layer of melted glass powder, and (ii) annealing the sealed photovoltaic module.

18. The method ofclaim 17, wherein the sealed photovoltaic module is annealed at a temperature less than a melting point and/or a softening point of the layer of melted glass powder.

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